I have written a couple of shows specifically for electronic instruments, along with others for acoustic instruments.

I remember that the Hammond Organ Company had to fight a protracted battle in the courts to be allowed to use the word "organ" in their title: real musicians insisted that the Hammond was not a real musical instrument.

It continues.

I would be surprised if a production of Wagner could achieve the needed results with synthesized playback -- the immediacy of response would be lacking.